This project is part of a multi-center effort to establish normative values for a daytime polysomnographic test of wakefulness. The primary objectives of this project are 1) to establish normative "control" or comparison data for sleep and wakefulness parameters against which diagnostic clinical data is measured; 2) to develop standardized testing protocols for the MWT and 3) to contribute to a multi-center effort to develop current normative control data for sleep and wakefulness.